The present invention relates to an antifouling structure effective to prevent contamination by such oceanic contaminants as barnacles, blue mussel and seaweeds and an antifouling method of protecting a certain structure against contamination.
Offshore structures in contact with seawater are always exposed to contamination by oceanic contaminants, resulting in appearance damage or malfunction. For instance, ships suffer a driving force drop when many forms of oceanic contaminants are deposited onto their bottoms, etc, and thermoelectric power plants are forced to stop operation when various forms of oceanic contaminants are built up on their seawater intake pits, because a serious problem arises in connection with the circulation of seawater serving as a cooling medium.
Among scores of techniques for preventing deposition of oceanic contaminants studied so far in the art, there is now available a method of protecting an offshore structure against contamination, in which the surface of that structure in contact with seawater is coated with a coating material containing cuprous oxide or organotin.
A grave problem with this conventional method, however, is that the coating material has a service life of as short as one year, since even when applied in the form of a thick layer, it is likely to peel away; there is needed troublesome maintenance work in which the coating material must be renewed per year.
The use of the organotin-containing coating material, because of its toxicity and its risk of being accumulated in fishery products, is undesired in view of preservation of the environment. In recent years, 10% nickel-90% cupronickel has been practically used, but this is far from the above-mentioned coating material in terms of antifouling effect, although excelling in serviceability.
A main object of this invention is to provide an antifouling structure which is free from the abovementioned problems or, in other words, is well protected against contamination and serves well over an extended period of time with neither need of any maintenance nor a risk of posing any toxicity problem. Another object of this invention is to provide a method of protecting a structure against contamination.